1. Field of the Invention
The present invention relates to a transmission control protocol/internet protocol (TCP/IP), and in particular to a transmission control apparatus and method employed to a data link layer of a TCP/IP suite.
2. Background of the Related Art
The Internet protocols are the most popular open network protocol suite because they can be used to communicate across any set of interconnected networks and are well suited for LAN and WAN communications. The Internet protocols consist of a suite of communication protocols, of which the two best known are the Transmission Control Protocol (TCP) and the Internet Protocol (IP).
IP is a network layer (layer 3 of the 081 reference model) protocol that contains addressing information and some control information that enables packets to be routed. Also, IP provides connectionless and best-effort delivery of packets through an internetwork, and provides fragmentation and reassembly of the packets to support data links.
TCP is a transport layer (layer 4 of the 081 reference model) protocol that provides reliable transmission of data in an IP environment. More specifically, TCP offers reliability by providing connection-oriented, end-to-end reliable packet delivery through an internetwork and offers efficient flow control, which means that when sending acknowledgments back to the source, the receiving TCP process indicates the highest sequence number it can receive without overflowing its internal buffers.
In the TCP/IP model, however, functions of the network access layer at the bottom of the protocol TCP/IP stack corresponding the data link (layer 2) and physical layers (layer 1) of the OSI reference model are not specified, such that it is difficult to expect reliable transfer of data across physical media.